With due respect to cluttering Eric's thread with a different set of images, I suspect the following are an apt illustration of the challenges of how local atmospheric conditions can trash the output of the most high quality telephoto prime.
This morning I planned to set up the tripod and 800's, with Z9 and all the TC's, to photograph my cats after breakfast - around 0900. I still need more examples at somewhat longer distances... Two of the 3 cats had taken up an ideal position on an outside table, 35m from the tripod (the intervening substrate is cropped kikuyu lawn grass). Of course the elder gray cat had to follow me down the garden - curious as to what was happening. At least the ginger stayed prone....
I snapped a few frames as he closed to the MFD of the 800 f5.6E - within 10m. But the rest of the images taken with respective TC14's and TC2's at 35m are worthless. On this warming day, Heat haze had already rubbished my careful plans. Bear in mind, mist and termperature inversions etc can have similar impacts when subjects require 800mm and even shorter focal lengths. The problems increase steeply with subject distance.
All exported as jpg from HE*RAW with Nikon StudioNX, with no PP except exposure adjustment where necessary. 100% crops where pertinent.
To provide a benchmark, the following portrait of an inquisitive Helmeted guinea fowl [ISO2200 +1 stop, f6.3, 1/1600) - handheld VR-On - is a representative example of the quality of images out of my 800 PF on the Z9.
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Two examples of heat haze with the TC14 on the F and 800mm Nikkor (not bothering with 100% crops):
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800mm f5.6E FL + TC14 III @ 9m captured within the above sequences
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100% crop:
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